Facebook and Twitter users are complaining about their accounts being compromised and then being used to spam friends with suspicious "free iPad offers."

Twitterwarned users of the scam, Wednesday, saying that it was resetting passwords of affected users. "If you've received a message promising you a new iPad, not only is there no iPad, but also your friends have been hacked," Twitter said

The scam is also hitting Facebook users to, according to company spokesman Simon Axten. "It's affecting an extremely small percentage of people on Facebook, but we take all threats seriously," he said via e-mail.

Gerome Stevens discovered that his Twitter account had been used to direct message contacts late Wednesday. He's not sure how the scammers got into his account, but they sent direct messages to his friends, that said, "u have to check out this website its glitchin right now and sending out ipads to everyone for free!"

He said the messages continued, even after he'd changed his password.

The messages his friends received contained a link to better-gifts.net. That Web site asks for personal information, and then directs the user to a variety of promotional offers from legitimate companies such as Netfilx, the Doubleday Book Club, and Columbia House DVD.

Online marketing programs pay cash for Web traffic, and hackers have found that by phishing victims and then using that information to break into legitimate Twitter and Facebook accounts, they can earn money.

This type of spam is particularly effective, because the messages appear to come from a trusted source.

Robert McMillan covers computer security and general technology breaking news for The IDG News Service. Follow Robert on Twitter at @bobmcmillan. Robert's e-mail address is robert_mcmillan@idg.com